Electric heater



June 7, 1932. J. c. WOODSON 1,851,464

ELECTRIC HEATER Filed April 11, 1929 INVENTOR Jmes 6i A/ooosorz ATTORNEY Patented June 7, 1932 UNITED STATES PATENT OFFICE JAMES C. WOODSON, OF MANSFIELD, OHIO, ASSIGNOB TO WESTINGHOUSE ELECTRIC & KAN UFACTUBIN G COMPANY, A CORPORATION OF PENNSYLVANIA ELECTBIO HEATER Application filed. April 11, 1929. Serial No. 854,280-

compact, simple and highly eflicient heater for heating tubular members of varying lengths.

Another object of my invention is to provide a tubular electric heater that shall embody means for cooling that portion of the heater that is not located within a hollow object being heated.

Another object of my invention is to provide a portable tubular heater that shall emll body means for carrying the same and also means for limiting the movement of a cooling means, adjustably located thereon, in one direction.

In practicing my invention, I provide an elongated tubular heater comprising an outer metallic sheath, a helically-wound resistor member insulatedly located within the sheath, a terminal box secured to one end of the heater, a control switch and a carrying means supported by the terminal box, and a cooling means that may be adjustably clamped on, and cover a portion of, the surface of the tubular heater.

In the single sheet of drawing,

Figure 1 is a view, in longitudinal section through a portion of the heater, taken on the line 1-1 of Fig. 2,

Figure 2 is a plan view, or one end of a tubular heater embodying my invention, and

Fig. 3 is a view, partially in plan and partially in section, of the other end of such a heater.

In the construction and assembly of relatively large fluid-turbine casings, it is highly desirable that the flange portions of co-acting sections of the casings be held tightly clamped relatively to each other in order that no leakage of the motive fluid may occur. Tubular bolts are used and it is desired to heat these bolts, either just before they are located in their proper operative positions in the aligned openings in the flanges of adj acent turbine sections or while they are in their proper operative positions, in order that the nuts thereon may be drawn up as tightly as possible while the bolts are hot, after which the bolts are permitted to cool, whereb a greater clamping action may be obtained t an would otherwise be the case.

A portable heater for heating tubular bolts embodies a substantially tubular heating unit 12 having an outer metal casing 13 and an enclosed helically-wound resistor 14, which is embedded in suitable electric-insulating material 16. The tubular member 12 may be of any suitable or desired length, corresponding to the maximum length of a tubular bolt 17 which it is desired to heat. The helically-wound resistor 14 extends through a portion only of the length of the outer metallic casing 13, as is shown more particularly in Fig. 2 of the drawing. Terminal leads 18 and 19 extend through the other portion of the casing 13 and into a terminal box 21 which is so designed and constructed that it ma be mounted on, and supported by, one end 0 the metallic casing 13 and be held thereon by a set screw 22.

The terminal box 21 includes a cylindrical portion 23 within which is located a suitable control switch 24, here shown as of the snapswitch type. The depth of the cylindrical member 23 is made large enough so that the handle 26 of the snap switch is protected thereby.

A. twin conductor cord 27 may be of any suitable or desired length and of such current carrying capacity as may be required by the amount of energy which is translated into heat in the resistor 14;. The inner end of the cord 27 extends into the terminal box 21 through a bushing 28 of any suitable electricinsulating material and may be provided with a knot 29 in order to prevent the cord slipping or pulling out from the terminal box and thus exerting a strain upon the connections between the cord, the terminal members of the switch 24: and the ends of the ter- 'minal leads 18 and 19.

secured against lugs 32 provided on the outside of the terminal box.21.

I have shown a hollow bolt 17 as being 10- Ell cated in aligned 0 enin s in two adjacent flanges 33 and 34, w ich flanges are intended to represent the flanges of adjacent sections of a large turbine casing. A nut 36 is located on the other end of the body of the bolt 17 and is to be tightened as much as possible thereon after bolt 17 has been heated in order to tightly clamp the flanges 33 and 34 together when the bolt cools.

As was hereinbefore stated, a heater of this type may be called upon to heat tubular objects of difl'erent lengths and, in order to provide means for cooling that part of the tubular heating unit which is not located within the tubular object, I provide a two-part clamp-on cooling means embodyin two elongated similar metal portions 3 and 38. These two metal portions are located in op posed facing relation and are held in tightly clamped location in a predetermined position on the tubular member 12 by means of pairs of clamping bolts 39 and 41, each pair being located adjacent to one end of the members 37 and 38, nuts 42 and 43 being provided thereon in the usual manner. When the two parts 37 and 38 are located in opposed relation, an opening is provided therebetween of substantially circular shape in lateral section and of such dimension as to permit of the tight clamping relation. A plurality of laterally extending fins 44 are provided on each of the portions 37 and 38 in order to increase the heat-radiating or cooling surfaces of these members, the number and spacing of such fins being such as to obtain the desired result; namely, to maintain the temperature of that part of the heating unit not located within the tubular object at a relatively low value which will not injure the resistor and the insulation.

Means for limiting the movement of the clamp-on cooling means in one direction longitudinally of the unit 12 embodies a pair of chains 46 and 47 one end of each of which is secured to the end of the corresponding leg portion of the carrying means 31, while the other ends of these chains are secured to the rear ends of the members 37 and 38, as by screws 48.

While I have shown the tubular heating unit embodying my invention as located in operative relation to a hollow bolt, it is, of course, obvious that its use is not restricted thereto and that it may be used for the heatin of any hollow objects or appliance.

- flhe device embodying my invention thus provides a relatively simple, lightweight, portable, tubular heating unit adapted to be operatively related to, and have any prede termined portion of its length inserted within, a hollow object to be heated, that portion of the heating unit which is not enclosed by the hollow object being provided with an adjustable clamp-on cooling means to ensure that the temperature of the unused portion of the heater shall also be below a. value which might prove dangerous to the resistor.

Various modifications may be made in the device embodying m invention without departing from the spirit and scope thereof, and

desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

I claim as my invention:

1. A portable electric heater including a straight tubular heating unit, a terminal box secured to one end of the tubular heating unit, a control switch for the heating unit in said terminal box, carrying means secured to the terminal box, cooling means for apart of the heating unit ad ustably securable thereon and means opcratively connecting the carrying means and the cooling means for limiting the adjustable movement of the cooling means in one direction.

2. A portable electric heater including a straight tubular metal-clad heating unit, a portion of whose lengths is to be inserted in a hollow object to be heated, and a twopart clamp-0n metal cooling means located on that part of the tubular heatin unit located outside of the object being heated to prevent excessive temperature rise of that part of the heating unit located outside of the object being heated.

3. An electric heater including an elongated tubular heating unit and a cooling means for a portion of the heating unit including a two-part structure to surround a predetermined portion of the length of the unit less than its total length and means for adj ustably clamping the cooling means on the heating unit.

In testimony whereof, I have hereunto subscribed my name this 3rd day of April, 1929.

JAMES C. WOODSON. 

